Electric condensers



NV17,1959 y A.NoYEs,JR 2,913,646

' ELECTRIC coNDENsERs Filed Feb. 8. 1956 2 Sheets-Sheet l ,co7 INVENTOR.

Nov. 17, 1959 A. NoYEs, JR 2,913,646

ELECTRIC CONDENSERS United States Patent O ELECTRIC CONDENSERS AthertonNoyes, Jr., Mountain Lakes, NJ., assignor, by mesue assignments, toAircraft Radio Corporation, a corporation of New Jersey (1958)Application February 8, 1956, Serial No. 564,170

6 Claims. (Cl. 317-254) This invention relates to electric condensersand aims to provide a variable electric condenser whose capacity isaccurately predetermined and made insensitive to temperature variations.

It has been found that even though the thermal expansion of the shaftand the frame of a condenser are equal, objectional changes in thecapacity will occur under the iniluence of thermal expansions andcontractions of the condenser parts, unless the tixed plates are locatedaccurately parallel to, and exactly centered between, the rotary plates.The object of the present invention is to provide for an initialadjustment of the fixed plates which shall comply with these twodesiderata.

In accordance with the invention, the xed plates are mounted in groupsbetween transverse partitions or septums of the condenser frame formicrometric translational and turning adjustment. An important featureof the invention consists in making such adjustments in relation to apoint and a plane which are xed in relation to the planes of the movableplates.

The invention will be described in connection with a condenserembodyingit and shown in the accompanying drawings in which Fig. 1 is a plan viewof the condenser;

Fig, 2 is a transverse section on the line 2-2 of Fig. l;

Fig. 3 is a transverse section on the line 3-3 of Fig. l;

Fig. 4 is an enlarged longitudinal section of a part of the condenser onthe line 4-4 of Fig. 5;

Pig. 5 is an enlarged plan view of the part of the condenser between twotransverse partitions or septums,v

showing parts in section;

Fig. 6 is a detail sectioned on the line 6--6 of Fig. 5; and

Fig. 7 is a fragmentary section on the line 7-7 of Fig. 5.

The condenser illustrated has a frame 10 provided with transverseseptums 11. In the frame is mounted a rotary shaft 12 to which therotary plates 13 of the condenser are secured. End shake of the shaft 12is prevented in the usual manner by a spring 15.

The iixed plates are mounted in groups between the septums 11. Eachgroup of xed plates is provided at opposite sides with supporting rods21 of micrometrically adjustable length.

Each supporting rod 21 consists of a hollow or tubular portion 22containing evenly spaced external grooves 23 in which the plates 20 aresecured by soldering. Each rod 22 has a bore which is of differentdiameters in two end portions of the rod. The smaller portion of thebore 24 is internally threaded. An adjusting screw 25 engages thethreads 24 and has an enlarged cylindrical head 26 which fits in thelarger portion 27 of the bore in the rod 22. An opening 28 in the rod 22provides access to sockets 29 in the head 26 of the screw for theinsertion of an adjusting tool.

The head 26 of the screw 25 has at its outer end a circular socket 30for the reception of a ball 31 of glass or other hard insulatingmaterial. A similar socket 2,913,646 Patented Nov. 17, 1959 32 isprovided at the end of the rod 22 which contains the threaded bore.

The stator consisting of the fixed plates 20 and the adjustablesupporting rods 21 is mounted between two septurns 11 of the frame.Sockets or bearings 35, 36 for the balls 31 at one end of the stator areprovided in one of the septums 11, while sockets or bearings 37, 38 forthe balls at the-other end of the stator are provided in a leaf spring39 pivotably mounted on a stud 40 on the next septum 11. The socket 35is circular and holds the ball which is in engagement with it in a fixedposition with respect to the frame 10. The socket 36 is a straight slothaving its axis directed towards the center of the socket 35. Thesockets 37 and 38 are also straight slots and they have their axes on adiametrical line of the spring 39, that is, on a line passing throughthe axis of the pivot stud 40. The form and arrangement of the socketsserve to make the stator adjustable in a xed plane and about a fixedpoint in this plane. The fixed plane is defined by the centers of thesockets 35 and 36 and the center of the stud 40. The xed point is thecenter of the circular socket 35. Both the plane and the point are fixedwith respect to the frame 10 and, therefore, in respect to the planes ofthe movable plates 13.

To avoid any play in the bearing of the spring 39 on the stud 40, thehole for the stud is formed in a slot 41 and a parallel slot 42 isformed in the spring 39 in one side ofthe slot 41. Prior toheat-treating of the spring, a tool inserted in the slot 42 is used todeform the portion of the spring between `the slots inward toward thestud hole, thus insuring that when mounted on the st ud the spring willbe free of translational play, yet still free to rotate to conform tothe required reference plane.

The stator is adjusted by turning the screws 25 by means of aninstrument inserted in the holes 29. Translational adjustment isobtained by turning both screws the same amount in the same direction.Rotational adjustment is obtained by turning one of the screws withrespect to the other.

The two adjustments are made after the condenser has been completelyassembled so that the correctness of each adjustment may be determinedby electrical measurement. Each adjustment is made in such a way as toobtain minimum capacity for the section of the condenser being adjusted.This insures positioning the fixed plates accurately parallel to themovable plates and placing them in the middle of the spaces betweenpairs of the movable plates.

After this adjustment has been accurately made, a change in thetemperature of the condenser has a minimum effect on the capacity of thecondenser. Furthermore, wherever the balls may be seated in the slots,good mechanical stability is maintained regardless of minor inaccuraciesin the manufacture of the parts.

What I claim is:

1. In an electrical condenser, the combination with two septums of asupporting frame, of an adjustable stator comprising a series of plates,two hollow supporting rods attached to said series of plates at oppositesides thereof, a part of each rod being internally threaded, a screwthreaded into the threaded part of each supporting rod, each rod andeach screw having at its outer end a circular socket, a ball ofinsulating material engaging the socket at each end of each rod, acircular socket in one of the septums for the ball at one end of one ofthe rods, a socket in said septum for the ball at the corresponding endof the other rod having the form of a straight slot directed toward saidcircular socket, a leaf spring pivotably mounted on the other septum,and radial slots in said spring for receiving the balls at the otherends of the two rods.

2. In an electrical condenser, the combination with two septums of asupporting frame, of an adjustable stator comprising a series of plates,two hollow sup- POIIIlg IOdS attached to said series of plates atoppositeV sides thereof, a part of each rod being internally threaded, ascrew threaded into the threaded part of each supportingl rod, each rodand each screw having at its outer end a circular socket, a ballof'insulating material engaging the socket at each end of each rod, acircular socket in one of the septums for the ball at the screw end ofone of the rods, a socket in said septum for the ball at the screw endof vthe other rod having the form of a straight slot directed towardsaid circular socket, a leaf spring pivotably mounted on the otherseptum, and radial slots in said spring for receiving the balls at theother ends of the two rods.

3. In an electrical condenser having a frame with transverse septums andhaving movable plates mounted on a shaft extending through said frame,an adjustable stator unit between two ofV theV septums of the framecomprising a setvof plates, two supporting rod assemblies secured toopposite sides of the set of plates, each assembly having fixed meansproviding a xed bearing surface at one end thereof and adjustable meansproviding an axially adjustable bearing surface at the other endthereof, a xed pointA bearing in one of the septums supporting theadjustable means of one assembly in engagement with the bearing surfacethereof, straight elongated slotV bearings with the greater lengththereof directed substantially in a common planepassing through thelongitudinal axis of both said assemblies for supporting respectivelythe fixed means and other adjustable means in engagement with thebearing surfaces thereof, and resilient means cooperating therewith forurging the bearings associated with the fixed means towards thebearings'at the opposite ends of the assemblies.

4. In an electrical condenser, the combination with two septums of asupporting frame, ofan adjustable stator comprising a series of plates,two supporting rod assemblies secured to opposite sides of said seriesofV plates, each assembly having fixed means providing a'iixedbearingsurface atone end thereof and adjustable means providing anaxially adjustable bearing surface at the other end thereof, a iixedpoint bearing in one of the septums supporting the adjustable means ofone assembly in engagement with the bearing surface thereof, a bearingin said one septum for supporting the adjustable means of the otherassembly in engagement with the bearing surface thereof and consistingof a straight slot'directed towards said point bearing, aleaf springpivotally mounted on the other septum, and bearings in saidspring forsup porting respectively the xed means in engagement with the bearingsurfaces thereof, each of the bearings in the spring comprising astraight slot directed towards the pivotal axis of the spring'.

5. In an electrical condenser, the combination with two septums of asupporting frame, of an adjustable stator unit comprising a set ofplates, two supporting rods secured to opposite sides of said set ofplates, each of said rods having balls of insulating material disposedat opposite ends thereof and means cooperating therewith for axiallyadjusting one of the balls while the other ball remains fixed relativeto the rod, a circular socket in one of the septums for the axiallyadjustable ball associated with one of the rods, a socket in said oneseptum for the axially adjustable ball associated with the other rodhaving the form of a straight slot directed toward said circular socket,a leaf spring pivotally mounted on the other septum, and radialV slotsin said spring for receiving respectively a different one of the fixedballs associated with the two rods.

6. In an electrical condenser having a frame with transverse septums andhaving movable plates mounted on a shaft extending through said frame,an adjustable stator unit between two of the septums of the framecomprising a set of'platestwo supporting rodassemblies secured toOpposite sides ofthe set of plates, each assembly, having fixed meansproviding a iixed bearing surface at one end thereof and adjustablemeans providing an axially adjustable bearing surface at the other endthereof, a fixed point bearing in one of the septums supporting theadjustable means of one assembly in engagement with the bearing surfacethereof, a straight slot bearing in said one septum directed toward saidpoint bearing for supporting the adjustable means of the other assemblyin engagement with the bearing surface thereof, a leaf spring mounted onthe other septum, and'straight slot bearings in said spring directedtowards each other for supporting respectively the fixed means inengagement with the bearing surfaces thereof, said spring urging saidassemblies toward the bearings in said one septum.

References Cited in the iile of this patent UNITED STATES, PATENTS1,579,482 Jorgensen Apr. 6, 1926 1,756,447 Behringer Apr; 29, 19302,077,544 Behr Apr. 20, 1937 2,282,215 Drake May'S, 1942 FOREIGN PATENTS701,991 Great Britain Ian. 6, 1954l

